51 replies to this topic

[landmaxdriver]

Hi everyone!
I've been reading through Turner Boy's various speed project threads and its given me the bug lol so i'm going to give it a go with my little mardave. But I won't be doing anything on the scale of Turner! This is a low budget project for a bit of fun and plus I don't have a machining god at my disposal I'm hoping to get 50mph out of this maybe a bit more
It has a homemade chassis which is wider and stiffer than the original with larger foam tyres on the rear and the stock ones up front. The motor is a 3000kv E-Pro with a 60A esc and will be using a 7.2v nimh for now because I can't afford lipos! Will give it a go with a friends lipos eventually.
I'm just waiting to get the pinion, deans connectors and bullet connectors off a friend before I can get this moving under its own steam. I'm going to start out with a 25t pinion and a 50t spur but may end up switching to a 30t pinion if I need more speeed
On a 25t pinion it will be geared for a theoretical top speed of 64mph so it will hopefully top out around 50 ish, thats if I can keep the damn thing in a straight line!
So here is how it was when I got it the other day. I will add more pictures once I have finished making the esc mount



Thanks for reading and if you have any ideas then let me know

Greg

EDIT: Finished the esc mount, what do you reckon guys? on top of the mount or under it?

or this?

Edited by landmaxdriver, 24 December 2011 - 05:17 PM.

[ch!ef]

nice idea buddy id like to see what you can get it to do.

just so you know i dont think you will get a 25t 32dp pinion on there with a 50t spur gear not sure what size the biggest is you can get on either ive ran an 18t which was the biggest i could lay my hands on and it was quick.

the shell you have should be fine just stick some tape over the gaps on the rear arches and stick a nice wing on the back for max down force to keep it planted.

with the esc put it toward the front of the car to give it alittle weight up front same goes for the rx and probably a small amount of weights too.

will you be running it on smooth tarmac? no stones etc? you may fine with it been a ministox chassis (no sus on it) it will bounce about compared to a v12 with sus on it i maybe wrong though with it been a fibreglass chassis

[landmaxdriver]

Ah right, I will see whether it will fit! If not then I can always dremel the motor mount to give it some more space to fit I think.

I will probably end up reconstructing the rear arches with some thick card or plastic, but I will leave a small gap to let some air in for cooling because the motor will probably get quite hot on tall gearing. Would a wing be needed seeing as it has a basic one already?

That's a good idea actually, thanks! I was thinking it was quite light at the front and thought it might bounce about so I will find somewhere to put the esc nearer the front, the only problem is that space is quite limited on these things!

Yeah I will be running on smooth tarmac, shouldn't be any stones but I will check before I run it. The chassis being grp has got some torsional flex in it which gives a crude form of suspension but I have no idea how good it will be at speed

Many Thanks
Greg

[Turner Boy]

Hey Greg, nice to see ive had some positive impact somewhere

Looking goog, will be following this one, top tips, try and aviod a wing, ch!ef is 100% correct, however, woth no sus, you run the risk of it flipping, all the weight you can upfront, and avoid the extra shell weight, make sure the shell is trimmed at the rear to allow airflow out, and try run on a smooth a surface as possible!

If you need any help, gimme a shout, really hope you get that you want from it, if you want 50, gear for over 70

Also, will your esc take 3s, if so, PM me, i has a treat for you

Merry christmas,

Scott

Edited by Turner Boy, 25 December 2011 - 09:21 PM.

[ch!ef]

reason for a wing on the beetle shell is downforce is pants trust me ive used one for racing the back end was everywhere that thing on the back isnt enough,mardaves need a rear wing for downforce look at mardave hotrod racing everyone runs 1,

im thinking of making my own electric drag car but the plans for this wont be while 2013

[Turner Boy]

the downforce doesnt kick in from a wing untill higher speeds, it will be slippery witout one, but its only supposed to be going in a straight line, so shouldnt need the extra down force, It is more likely just to add drag, he says lol

[landmaxdriver]

Thanks for the replies and advice guys its much appreciated!

I think I'll give it a few runs without the wing first and if I need one then I can always buy one or make one for it I may end up buying a hot rod shell for it that has a big wing on it which would have better aerodynamics.

Thanks for the tip on the gearing mate, will see if I can get my hands on a 30t pinion

Thanks
Greg

[ch!ef]

thing is there is no suspension on it so the slightest rise or drop on the tarmac will throw its back end thats why you will need a wing.

yes it will apply more drag but it dont need to be a humongous thing try low and high downforce 1s see which you find is better to keep its back wheels in line. if you have super grippy tyres you wont need 1 but with mardave foams you will probably need 1 also stick some foam tyre additive for tarmac on them if you can get some that will help with grip.

[landmaxdriver]

Okay that makes sense mate, will give it a go and see what it needs
The tyres on it are foam but have a rubber thing over the top and are very very grippy, not sure if it will be enough though, I will experiment with it once I have my pinion and connectors and I'll let you know mate

Greg

[biggusditchus]

Should definitely be interesting, had experience in the past with running a mardave with 6 cells on a custom chassis with a 12turn motor (long before brushless then) and it absolutely flew.    Was almost impossible to get it to full power without it spinning out unless you have an immensely long, straight, flat piece of tarmac that was with a diff from a 1/12 pan car.

[Turner Boy]

Very true there, maybe more of a stabalising wing opposed to a down force wing, would be useful

But yeah, without sus, you will struggle, thats the issue, my M03 has no sus travel, as ive dropped it on really short, hard sprimngs, to gt it to go better, which it does, however one little piece of grit throws it off its just personal preference, mine is no wing, nice and slippery, ch!ef must like his cars to handle well

All the advice here is sound, just finding what works for you Greg Im sure your car will let you know

[danny boy]

50mph was my target Landmaxdriver   You Already know that though. Ive changed my plan after abit after seeing this http://hawaiiscalemo...php?topic=124.0 . Hope you make your target, good luck

[landmaxdriver]

The thing with your MO3 is that its front wheel drive so it doesn't spin if you gun the throttle which helps! Bet you get loads of wheel spin

Handling is not so much of an issue because its only going to go in straight lines for now! But some grip off the line and high speed stability would be nice! Hope I'm not asking too much from the little mardave though!

To be honest I think its just a case of experimenting and seeing whether it needs more weight or more downforce etc

And Danny, your car will do 50 no problem reckon you can do more quite easily!

Many thanks for all the replies!

Greg

[danny boy]

thanks mate. how did you work out the theoretical speed of 64mph?

[landmaxdriver]

I used this site mate http://scriptasylum..../top_speed.html its easy on the mardave because the final drive ratio is 1 but it gets more complicated when you have diffs

Edited by landmaxdriver, 26 December 2011 - 05:50 PM.